Ronnie O'Sullivan will not be defending his UK Snooker Championship title in York in November.
The deadline to enter the tournament, which begins on 24 November, was 28 October, but the 39-year-old five-time world champion has declined to enter.
He has not played in a competitive match since losing 13-9 to Stuart Bingham in the quarter-finals of the World Championship in April.
O'Sullivan beat Judd Trump 10-9 in last year's final to win his fifth UK title.
This month, O'Sullivan also announced he would not be defending his title at the Champion of Champions event in Coventry, which begins on 10 November.
The UK Championship is broadcast live by the BBC and is one of snooker's 'Triple Crown' events, along with the Masters and the World Championship.
O'Sullivan's withdrawal will disappoint many fans of the popular competition, which is staged at the Barbican Centre.
A spokesman from World Snooker, the sport's governing body, said they were still expecting "a great event" and that ticket sales were "extremely good".